The present invention relates to a winding device for cables, particularly to a configuration of grooves formed in the outer circumference of a take-up drum for guiding cables to be wound round the take-up drum.
In an automobile window regulator of the wire driving type, for example, such a winding device for cables as shown in FIGS. 1 and 2 has been used for winding cables such as steel wires.
This winding device is provided with a cylindrical take-up drum 55 which rotates in combination with a rotary shaft 54 rotatable in either direction by means of an operating handle or a driving motor (both not shown in the drawings), said take-up drum being mounted within a support 53 comprising a box-shaped casing 51 which has an opening facing downwardly in the drawing and a base plate 52 which closes the opening of the casing 51. The upper and lower portions of the outer circumference of the take-up drum 55 are provided with grooves 56, 57, said grooves having a V-shaped or U-shaped cross-section and formed in spiral in the same direction, in which cables 60, 61, such as wires, are drawn from openings 58a, 59a formed at each end of a pair of guide tubes 58, 59. The openings 58a, 59a face take-up drum 55, said guide tubes being secured to one end part of the casing 51, and the cables 60, 61 are wound round the outer circumference of the take-up drum 55 along said grooves 56, 57 in opposite directions to each other.
The numerical references 62, 63 designate bores for leading each end of the cables 60, 61 respectively into the inside of the take-up drum 55 and fastening them therein.
In such a conventional winding device for cables as mentioned above, as clearly illustrated in FIG. 2, since the groove 57 for guiding the cable is formed in the outer circumference of the take-up drum 55 such that angles .theta..sub.1,.theta..sub.2 between each side wall 57a, 57b and a normal line H perpendicular to the rotational axis of the take-up drum 55 are always substantially equal (.theta..sub.1 =.theta..sub.2), there are problems in winding the cable 61 round the take-up drum 55 at a certain point O located far from the opening 59a as shown in FIG. 1. The problems include chafing of the cable 61 against the side wall 57a of the groove 57 and on the side of the opening 59a which may cause unusual noise and/or the cable and the side wall to be worn severely.
The groove 56 also suffers the same problems as with the groove 57, though not shown in the drawings, because it is constructed symmetrical in relation to the groove 57.
As a solution to the above mentioned problem, it is considered to increase the angle .theta..sub.1 +.theta..sub.2 between each side wall 57a, 57b of the groove 57. However, with this arrangement, pitch P of the groove 57 would become large and the length of the take-up drum 55 must be made longer, so that there would be other problems such that the entire body of the device becomes too large in size.